EQUISTAR CHEMICALS, L.P.

Incident Narrative

LYONDELLBASELL EQUISTAR MAINTENANCE TECHNICIANS WERE REPORTING TO STRATTON RIDGE FOR ROUTINE INSPECTIONS. UPON ARRIVAL AT 7:20 A.M. THEY SAW WHAT APPEARED TO BE ETHYLENE VAPORS COMING FROM THE DOOR TO ONE OF THE FILTERS. UPON OPENING THE DOOR, THEY NOTICED AN ICE BALL HAD FORMED AROUND THE 3/4 INCH O-RING GASKET AND FILTER CABINET DOOR AND A VAPOR CLOUD EMITTING FROM THE ICE BALL. THEY IMMEDIATELY SWAPPED FILTERS AND BLOCKED IN THE FILTER THAT HAD THE LEAK AND STARTED DEPRESSURING THE SYSTEM. A CALL WAS MADE TO THE CONTROL ROOM AT 7:28 A.M. AFTER DISCUSSIONS WITH FIELD TECHNICIAN AND ENGINEER, IT WAS DETERMINED THAT WE WOULD EXCEED THE 5 GALLON REPORTABLE QUANTITIES THRESHOLD. THIS IS A REGULATED INTRASTATE PIPELINE IN BRAZORIA COUNTY. AFTER THE SYSTEM WAS DEPRESSURED AND REPAIRS WERE MADE IT WAS DETERMINED THAT THE LEAK WAS FROM THE 3/4 INCH O-RING ON THE FILTER. REPAIRS WERE MADE AND SYSTEM IS BACK TO NORMAL. PRELIMINARY INVESTIGATION FINDINGS: OUR INVESTIGATION'S PRELIMINARY FINDING DETERMINED THE LEAK WAS DUE TO FAILURE OF AN O-RING GASKET ON AN ORIFICE PLUG IN A FILTER DOOR MECHANISM. THE FAILURE OF THE GASKET WAS DUE TO MATERIAL DEGRADATION RESULTING FROM THE AGE OF THE GASKET COMBINED WITH EXPOSURE TO ATMOSPHERIC CONDITIONS AND ETHYLENE SERVICE AND POSSIBLY MECHANICAL STRESS DUE TO POSSIBLE REUSE OF THE GASKET. OUR EXISTING MAINTENANCE PROCEDURE FOR INSPECTION AND REPLACEMENT OF ETHYLENE FILTER ELEMENTS DOESN'T SPECIFY INSPECTION AND REPLACEMENT OF ORIFICE PLUG GASKETS OF THIS TYPE. PLAN TO PREVENT RECURRENCE: IN THIS INSTANCE, THE PLUG WITH THE O-RING GASKET WAS REPLACED WITH A CAPPED SECTION OF PIPE WITH FULL THREADING WHERE IT CONNECTS TO THE FILTER HOUSING. THE INVESTIGATION WILL ALSO RECOMMEND UPDATING THE MAINTENANCE PROCEDURE TO INCLUDE A SPECIFICATION FOR REPLACING GASKETS ON SIMILAR ORIFICE PLUGS.